There is a conventionally known high-frequency treatment in which a high-frequency current is passed through a treatment part, and this electrical energy is used to perform various treatments to a living tissue, such as cutting it off. Among the most commonly known high-frequency treatment tools are a monopolar (single electrode) type, which includes a treatment electrode (first electrode) provided at the treatment part and a passive electrode (second electrode) disposed outside the body of the patient, and a bipolar type, which includes the passive electrode disposed at a distal end of the treatment part.
In a bipolar high-frequency treatment tool, due to the close proximity between the treatment electrode and the passive electrode, shorting caused by contact between them is more likely to occur than in the monopolar type. When a short occurs, treatment cannot be performed to the living tissue. Therefore, it is important, in a bipolar high-frequency treatment tool, to ensure that there is sufficient insulation between the treatment electrode and the passive electrode, particularly during the treatment.
One example of a structure for ensuring insulation between the treatment electrode and the passive electrode is, for example, the bipolar high-frequency treatment tool disclosed in Patent Document 1. In this high-frequency treatment tool, an insulating tube is inserted into an outer tube with a passive electrode attached to its distal end, and a driving wire with a treatment electrode provided at its distal end is inserted into the insulating tube. The insulating tube is adhesively fixed such as to cover the inner peripheral face of the passive electrode, and its presence between the treatment electrode and the passive electrode ensures that they are insulated from each other.